On the Steam store they've done a great job with their certification program for the Steam Deck.
Also, I don't think their target market is people who don't own any Steam games yet. It's going to be people with already extensive back catalogues on Steam.
I disagree. I see this becoming an Xbox/PlayStation killer/contender.
They currently don’t accept orders from people without an existing Steam purchase from before May. (Otherwise I might have been interested.)
I imagine that this is primarily for preorders and will be dropped as soon as there is sufficient stock.